Baobab (Adansonia digitata) is a deciduous tree, coming from the dry parts of central Africa and appears mostly in tropical countries, principally as a component of secondary forests.
The origin of plants of the genus Adansonia is probably located in Madagascar where several endemic species have been described and where Adansonia digitata also exists. Other species of the mentioned genus have been found in east Africa and in Australia.
The different constituent parts of baobab were and still are used and exploited in Africa, either from an economic standpoint (the bark for the production of fibers and paper, the wood has a rubber coagulant and the roots as a red coloring material), or as food (more particularly seeds and young leaves) or again as medicine (the bark has astringent diaphoretic and even febrifugic properties; the wood and the seeks have antidysenteric and anti-inflammatory properties; the leaves are used as an antiperspirant, against kidney and bladder troubles and as an anti-asthmatic and emollient).
It is known that the leaves contain particularly mucilages which swell in the presence of water.
Baobab leaves (D. YAZZIE et al., Journal of Food Composition and Analysis, 1994, 7; 3, 198-19313 R. GAIWE et al., International Journal of Crude Drug Research, 1989, 27, 2, 101-104) contain, in addition to mucilages, mineral salts, proteins, catechic tannins and vitamin compounds (riboflavin, thiamine, vitamin C, niacin); a flavonoid-type compound has also been discovered.
Analysis of the amino acid composition indicates that the proteins of the leaves of baobab, which represent about 10.6% of the dry weight of the leaves, contain interesting quantities of the following essential amino acids: lysine, arginine, threonine, tyrosine, phenylalanine, tryptophane, methionine and cysteine.
These leaves constitute quantitatively and qualitatively a good source of food proteins.
Moreover, baobab leaves contain high quantities of calcium (3.07 to 30 mg/g of dry leaves) and substantial quantities of iron, potassium, magnesium, manganese, molybdenum, phosphorus and zinc.
The dry extractable mucilage content of the leaves varies and is of the order of 9 to 12% relative to the dry leaves, the principal constituents of these mucilages having molecular weights higher than 100,000.
A high interaction between the proteins and the polysaccharides is supposed.
According to the literature (M. L. WOOLFE et al., J. Sci. Fd. Agric., 1977, 28, 519-529), the chemical composition of the mucilages of baobab leaves has been established as follows:
40.2 g galacturonic acid/100 g of mucilages PA1 39.1 g glucuronic acid/100 g of mucilages PA1 9.3 g of neutral sugars/100 g of mucilages.
These neutral sugars, which are rhamnose, galactose, glucose and arabinose, are present in a mole ratio of 0.6-1-0.44-0.15.
The above data indicate a very high portion of uronic acids and few neutral sugars: these mucilages do not have pectic compounds or pectic type units.
Moreover, these mucilages have interesting rheologic properties, their viscosity decreasing with an increase in the temperature of extraction.